1. Field of the Invention
The present invention relates to a method of cooling a hot plate for heating a substrate and a heat processing apparatus.
2. Description of the Related Art
In the process of photo-resist processing in semiconductor device fabrication, various kinds of heat processing such as heat processing (pre-baking) after a resist solution is applied on the front face of a semiconductor wafer (hereinafter referred to as xe2x80x9ca waferxe2x80x9d), heat processing (post-exposure baking) after exposure of a pattern is performed, and the like are performed.
Such heat processing is usually performed by a heat processing apparatus. This heat processing apparatus has a disc-shaped thick hot plate made of aluminum in a processing container, and performs heat processing for the wafer by placing the wafer to be processed on the hot plate and heating the hot plate to a predetermined temperature by a heater incorporated in the hot plate.
Incidentally, there are cases where temperatures in heat processing are different, for example, the wafer is heated to 140xc2x0 C. or the wafer is heated to 90xc2x0 C. lower than this temperature, depending on the types of semiconductor devices to be formed, types of resist solutions, and types of processes, and the like. In these cases, for example, when the hot plate which has been performing heat processing at 140xc2x0 C. up to the present is used for heat processing at 90xc2x0 C., it is required to temporarily lower the temperature of the hot plate, for example, to 90xc2x0 C., in which case a conventional heat processing apparatus of this type is not specially equipped with a mechanism for cooling and the like, and thus the hot plate is cooled naturally.
However, if cooling is left only to natural cooling when the hot plate is cooled to the predetermined temperature, the temperature in the surface of the hot plate is lowered in an ununiform state, and a considerably long time is required for reaching the predetermined temperature and obtaining uniform surface temperature, which is undesirable. To improve this, if dedicated heat processing apparatus are previously prepared for respective processing temperatures, for example, 140xc2x0 C. and 90xc2x0 C., a problem of cooling time can be settled, but if so, a large number of heat processing apparatus become necessary, and as a result, a coating and developing apparatus in which usually a various kinds of resist processing apparatus are put together and used is enlarged, which is undesirable.
An object of the present invention is to provide a method capable of cooling a hot plate of a heat processing apparatus more rapidly than in prior arts, and a heat processing apparatus having a function capable of suitably carrying out the cooling method.
To attain the aforesaid object, according to a first aspect of the present invention, a hot plate cooling method, comprising the steps of: heating a hot plate for placing a substrate thereon and heating the substrate; and positioning an object of which a portion facing the hot plate has a color with good heat absorption efficiency above the hot plate is provided.
According to the aforesaid structure, the object of which the portion facing the hot plate has a color with good heat absorption efficiency is positioned above the hot plate, whereby radiant heat from the hot plate can be effectively absorbed, resulting in the promotion of cooling of the hot plate and uniform cooling.
According to a second aspect of the present invention, a heat processing apparatus, comprising: a hot plate for heating a substrate; and a nozzle for blowing cooling gas onto a rear face of the hot plate is provided.
According to the aforesaid structure, the temperature of the hot plate can be lowered more rapidly than in the prior arts, and moreover dust and the like do not adhere to a substrate mounting face since air is blown onto the rear face side of the hot plate.
According to a third aspect of the present invention, a heat processing apparatus, comprising: a hot plate for heating a substrate; and an object moving freely over the hot plate, of which a face opposite the hot plate has a color with good heat absorption efficiency is provided.
According to the aforesaid structure, the object of which the portion facing the hot plate has a color with good heat absorption efficiency can be positioned above the hot plate, whereby radiant heat from the hot plate can be effectively absorbed, resulting in the promotion of cooling of the hot plate and uniform cooling.
According to a fourth aspect of the present invention, an apparatus for performing heat processing for a substrate, comprises: a plate for holding the substrate; a heater for heating the plate; a cooling container containing a refrigerant; a cooling module, disposed to touch at least one face of the cooling container, for absorbing a heat from the cooling container to cool the refrigerant in the cooling container to a predetermined temperature by a Peltier effect; a supply source of a cooling gas; a cooling gas channel connected to the supply source, a portion of which is provided to touch the refrigerant in the cooling container and cooled by touching the refrigerant; and a nozzle for jetting the cooling gas which has passed through the cooling gas channel toward the plate.
In the aforesaid structure, the cooling gas cooled by the Peltier effect is supplied to the hot plate, thereby enhancing the cooling efficiency of the hot plate, and consequently the temperature of the hot plate can be lowered to a predetermined temperature in a short time.
According to a fifth aspect of the present invention, an apparatus for forming a resist pattern on a substrate, comprises: a coating processing unit for coating a front face of the substrate with a resist; a developing processing unit for supplying a developing solution to the front face of the substrate subjected to exposure to develop the same; a heat processing unit for heating the substrate after exposure to a predetermined temperature; and a substrate carrier for transferring the substrate between the coating processing unit, the developing processing unit, and the heat processing unit, the heat processing unit, comprising: a plate for holding the substrate; a heater for heating the plate; a cooling container containing a refrigerant; a cooling module, disposed to touch at least one face of the cooling container, for absorbing a heat from the cooling container to cool the refrigerant in the cooling container to a predetermined temperature by a Peltier effect; a supply source of a cooling gas; a cooling gas channel connected to the supply source, a portion of which is provided to touch the refrigerant in the cooling container and cooled by touching the refrigerant; and a nozzle for jetting the cooling gas which has passed through the cooling gas channel toward the plate.
According to the aforesaid structure, the temperature of the hot plate in the heat processing unit can be regulated in a short time, leading to a rise in throughput.
In a sixth aspect of the present invention, a method for forming a resist pattern on a substrate, comprises: a first resist pattern forming step of performing exposure processing for a substrate coated with a resist by use of a first reticle, heating the exposed substrate by a hot plate heated to a first temperature, and thereafter supplying a developing solution to a front face of the substrate to develop the same; a second resist pattern forming step of performing exposure processing for a substrate coated with the resist by use of a second reticle, heating the exposed substrate by the hot plate heated to a second temperature lower than the first temperature, and thereafter supplying the developing solution to a front face of the substrate to develop the same; a step of exchanging the first reticle for the second reticle, which is performed between the first resist pattern forming step and the second resist pattern forming step; a step of absorbing a heat from a cooling container by a Peltier effect of a cooling module to cool a refrigerant in the cooling container to a predetermined temperature; and a step of providing a cooling gas channel so that the cooling gas channel touches the refrigerant in the cooling container and supplying a cooling gas which is cooled by flowing through the cooling gas channel to the hot plate to lower the temperature of the hot plate from the first temperature to the second temperature.
In a seventh aspect of the present invention, a method for forming a resist pattern on a substrate, comprises: a first resist pattern forming step of performing exposure processing for a substrate coated with a resist by use of a first reticle, heating the exposed substrate by a hot plate heated to a first temperature, and thereafter supplying a developing solution to a front face of the substrate to develop the same; a second resist pattern forming step of performing exposure processing for a substrate coated with the resist by use of a second reticle, heating the exposed substrate by the hot plate heated to a second temperature lower than the first temperature, and thereafter supplying the developing solution to a front face of the substrate to develop the same; a step of exchanging the first reticle for the second reticle, which is performed between the first resist pattern forming step and the second resist pattern forming step; a step of absorbing a heat from a cooling container by a Peltier effect of a cooling module to cool a refrigerant in the cooling container to a predetermined temperature, which is performed during the first resist pattern forming step; and a step of providing a cooling gas channel so that the cooling gas channel touches the refrigerant in the cooling container and supplying a cooling gas which is cooled by flowing through the cooling gas channel to the hot plate to lower the temperature of the hot plate from the first temperature to the second temperature, which is performed during the step of exchanging the reticles.
According to these methods, the refrigerant in the cooling container is cooled to the predetermined temperature during the first resist pattern forming step, and the cooled cooling gas is supplied to the hot plate to lower the temperature of the hot plate from the first temperature to the second temperature during the step of exchanging the reticles, whereby the time to wait for temperature regulation of the hot plate need not be provided specially, resulting in improvement in throughput.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.